Representatives from both Apple and Google will testify at a Congressional hearing next month on consumer privacy and smartphones, two U.S. senators confirmed on Thursday.

"I'm pleased that Apple and Google have confirmed that they'll be sending representatives to testify at my upcoming hearing on mobile technology and privacy," Sen. Al Franken (D-Minn.) said in a statement issued today.

Franken, who chairs a new Senate privacy panel, added that the hearing was a "first step" in Congressional inquiries whether federal laws have kept up with the surge in mobile devices, including smartphones and tablets.

Sen. Patrick Leahy (D-Vt.), the chairman of the Senate's Judiciary Committee, also acknowledged the participation of the two firms. "It is essential that policy makers and the American people have complete and accurate information about the privacy implications of these new technologies," Leahy said in a separate statement.

Franken kicked off the inquiry last week on the same day that two British researchers reported that Apple's iPhone and 3G iPad concealed an unencrypted file containing thousands of location data entries going months. The unsecured file was also backed up on users' PCs and Macs during synchronization.

On Monday, Franken asked both Apple and Google to testify at his hearing. Wednesday, Leahy followed up with a letter to the two companies, urging them to accept Franken's invitation as he noted "deep concern that [Android Phones and iPhones] collect, store and track user location data without the user's consent."

While most of the focus has been on Apple and its iOS -- the mobile operating system that powers the iPhone and iPad -- Google's Android also collects location information from users' smartphones.

Yesterday, Apple denied that it tracked users but said it would make changes to iOS. Later in the day, CEO Steve Jobs told the Wall Street Journal and The New York Times that his company would participate at the hearing.

Meanwhile, Google has said it collects location data from Android phones only when owners opt-in. "Any location data that is sent back to Google location servers is anonymized and is not tied or traceable to a specific user," the company told the IDG News Service on Monday.

Earlier today, a crisis communication expert criticized Apple for taking a week to respond to questions about iPhone location tracking, saying that the company "dropped the ball in a big way."

And because Congress had gotten involved, Apple faces a long investigation into its privacy practices, predicted Michael Robinson, a senior vice president with Levick Strategic Communications, a Washington, D.C. firm that helps companies deal with public relations emergencies.

"This is in its nascent stage, it will be going on for a long, long time," Robinson said. "Apple has lots more to do on this, if only because Congress is going to have hearings."

Franken's hearing, which is set to begin at 10 a.m. ET on May 10, will also take testimony from officials with the U.S. Department of Justice and the Federal Trade Commission, as well as from Justin Brookman, director of consumer privacy at the Center for Democracy & Technology.

In an interview Wednesday with Computerworld, Brookman applauded Apple's acknowledgement of the privacy problem and its promise to modify iOS, but questioned the company's flat denial that it never tracked users.

"I'm glad that they are fixing what they call bugs," Brookman said. "But I take exception with their strong denial that they track users."